Ram-driven presses, e.g., punch presses, are well known in the art. Punch presses are typically configured to hold a plurality of tools for forming a variety of shapes and sizes of indentations and/or holes in sheet workpieces, e.g., sheet metal. Tools of this sort commonly include a punch and die. When a punch and corresponding die are mounted in a press and located in a working position of the press, e.g., beneath the ram (in some cases, coupled directly to the ram), the punch is driven, according to a pre-programmed ram stroke, to form an indentation or a hole through a sheet workpiece which has been located between the punch and die.
Such punch presses may be turret presses, single-station presses, or other metal fabricating presses. Turret presses, for example, commonly employ a rotatable upper table or “turret” that carries a plurality of tools (e.g., punches), and a rotatable lower table/turret that carries a plurality of dies. In contrast, single station punch presses generally do not have turrets, but rather have a single station adapted for pressing workpieces.
Regarding turret presses, when the upper and lower tables are rotated into a position where a particular male punch on the upper table is aligned with a particular female die on the lower table, a workpiece (e.g., a piece of sheet metal) between the two tables can be machined (punched, bent, etc.) by moving the punch downwardly into contact with the workpiece so that the punch deforms (or pierces) the workpiece. The downward movement of the punch is caused when a ram strikes an upper part (head or punch driver) of the punch.
As described above, with a conventional turret tool, when the ram of the turret press strikes the punch driver, a lower tip of the punch is driven forcefully downwardly into contact with a workpiece, which is then deformed (e.g., punched, bent, etc.) between the punch tip and the die. Thus, when the ram strikes the top of the tool (which is rigidly coupled to the tip of the tool), the tip of the tool is caused to move forcefully downwardly against the workpiece.
The die commonly has a recess into which the tip of the punch projects during the punching operation. In some cases, a hole is punched in the workpiece during the downstroke of the punch, from which the tip of the punch may shear through the sheet metal (in the process, the tip of the punch extends into the die's central recess). However, as is known, the punching operation can involve other machining or inspecting of the workpiece during the downstroke of the punch, such as bending, tapping, measuring, etc. of the workpiece.
Thus, in conventional ram-driven presses, the downward stroke of the ram into a tool causes acceleration of the tool. This acceleration of the tool facilitates an operation on a workpiece by the tip of the tool. While the ram stroke is found to impart sufficient dynamic energy to the tool to facilitate the necessitated operation by the tool tip, there are other more efficient, and in turn, more effective, means and methods of actuating the tool tip, with such means and methods being facilitated from energy derived from the tool's acceleration or from energy from other external sources.